Antiferromagnetic exchange coupling in amorphous Fe-Sc alloys

Results of Fe-57 Mossbauer, AC and DC susceptibility, grazing incidence X-r ay diffraction, resistivity and Rutherford-backscattering measurements on t he amorphous alloys Fe100-xScx (8 less than or equal to x less than or equa l to 70) give for the first time convincing evidence for the antiferromagne tic exchange coupling between Fe-moments. The antiferromagnetic coupling be tween Fe-moments is for 8 less than or equal to x < 20 limited to certain r egions (magnetic clusters) of the sample. The nature of the coupling is of the Heisenberg type. For 43< x < 50, the magnetic coupling between Fe-momen ts is across nonmagnetic Sc-atoms. The conduction electrons mediate an indi rect magnetic interaction between the Fe-moments. The magnetic exchange cou pling between Fe-moments across Sc-atoms is negative. The antiferromagnetic coupling between Fe-moments can be explained by the Ruderman-Kittel-Kasuya -Yosida, RKKY, interaction by taking into account the damped oscillatory be havior of the RKKY interactions.